This invention relates to method and apparatus for slitting rolled material. It has particular application to apparatus including a rotary shaft mounted and driven in a frame, having a clamping device and a slitting device, the so-called cutting frame, for the rolled material which is sluable to an axis parallel to the rotary shaft. This axis is slidable in adjustable spacings, and the clamping device consists of several movable sliders placed about the circumference and in guides of a disk rotating with the rotary shaft. The side of the disk directed to the rolled material is provided with clamping jaws for engagement with the outer side of the roll.
By relative movement produced between the cutting frame and the rolled material, a "drawing cut" is obtained by which even the thinnest and nonhomogeneous material is cut by the replacement cut, without fraying.
Such an application is described, e.g., in German Offenlegungsschrift No. 2 222 548 (Nov. 22, 1973), and has proved to be very reliable since rolls of practically every material can be slit. Generally, as a slitting tool, a knife with different kinds of cuts and cut techniques is used. However, a disk saw, e.g., can be utilized.
For the variety of synthetic materials on the market, it has been found as part of the present invention, advantageously, in addition to the above mentioned and reliable "drawing cut", to transmit or superpose oscillating movements to the slitting tool. For example, a roll of material consisting of soft sealing rubber with applied adhesive is provided, e.g., with thin hard paper or plastic sheets or the like for protection of the individual layer. While the often very porous rubber may be cut cleanly without any pressure, hard paper or silicone layers or the like require a very strong knife pressure for the cutting. When penetrating the hard paper, stalling of the knife through the porous rubber to the next hard paper strip is required and, as a result, the slit rolls do not have a plane cut, but are slit unevenly and wavy, thus rendering the same unusable. By superposed oscillations, the hard paper with only a soft pressure of the knife is cut easily; the knife thus cuts "delicately" through the hard material.
These additional oscillations to the "drawing cut" are preferably produced by an oscillator at 100 hertz, e.g. This oscillating element may be mounted, e.g., in front of the clamping device of the cutting frame, preferably in front of the rear knife support, from where it operationally transmits the oscillating movement to the knife. Alternatively, an oscillating element may also be mounted directly on the knife, e.g., to induce the oscillating movement therein. Depending upon the material, higher frequencies can be induced. The oscillations are preferably in the longitudinal direction of the knife, although other directions are possible.
By this combination of "drawing and oscillating cut", even the most difficult rolls of material can be slit to extremely narrow rolls. Also by this combination cut, in many cases a disk saw for materials not to be displaced is not needed. This results in cutting free of losses which otherwise cannot be avoided through the cutting width of the disk saw blade.
It is necessary, with known slitting apparatus as described above, that the rolled material slipped on the rotary shaft is connected torsionally with the driven rotary shaft. In this respect, the cited German Offenlegungsschrift proposes in an embodiment a clamping device which consists of two coaxial disks which are reversible opposite to each other. The inner disk is provided with circular guides with radial component. Sliders grip into these guides which are slidably fastened on the other disk. However, this arrangement has the disadvantage that, only to a small extent, can adjustment movements be achieved; such movements are particularly dependant upon the angle between the circular guides and the radius. The guides must be arranged relatively flat, i.e., adjacent to the tangent line, in order to obtain the desired sliding of the sliders in the guides.
In another embodiment of the cited German Offenlegungsschrift, the clamping device is provided by a disk to the inside of which pins are fastened, the latter gripping the rolled material. This attachment of the rolled material on the disk and thus at the driven rotary shaft, however, has only proved to be partially reliable, as this known clamping device cannot integrate all sources present during operation, particularly, when the rolled material is not wound with plane edges.
An object of the present invention, therefore, is to provide apparatus of the type described which includes a clamping device in which greatly differing diameter ranges of rolled material can be clamped quickly and safely. Moreover, difficult materials are cleanly slit, which is done satisfactorily with the "drawing and oscillating cut" described above.
For solving this problem, the present invention is characterized in that sliders are arranged in radially extending guides for engaging the outer surface of the roll, and are connected to a driven chain, and that for engagement of the inner surface of the roll on the rotary shaft at least one radially expandable supporting element is provided. The roll slipped on the rotary shaft is thus gripped from the inside and the outside, whereby the material sheets can be very safely supported in all layers. As both the inner and the outer diameters of the roll -- within a certain range -- are subject to fluctuation, according to the present invention the inner diameter is gripped by the radially expanding support element, and a great range of adjustment is achieved by the radially extending guides. The desired high pressure energy for the clamping jaws is provided by the chain drive of the sliders.
For the chain drive, it is preferred to fasten each slider to an endless chain which is in turn driven by a common endless driven chain. By this common chain, synchronization of movements of the sliders is achieved. Further, the chain drive construction also can be utilized to mount a transmission in the drive train to achieve, e.g., a reduction of speed. This is effected, e.g. by guiding the common driving chain and each of the individual clamping chains over one common shaft, on which gear wheels with different numbers of teeth are positioned.
The radially expandable supporting element for the inner clamping of the roll of material can be a tube piece consisting of elastic material, e.g., rubber, which is compressible in an axial direction. By compression in the axial direction, the tube is curved to the outside and thus grips the roll at the inner surface of its core. If compression is no longer present, then the tube piece through its elastic properties resumes its normal, original and non-gripping position.
Instead of this supporting element, or in addition thereto, the complete rotary shaft can be provided with an adjustable diameter in order to provide an expandable rotary shaft. For example, the radially expandable supporting element may consist of shells about the outer surface of the rotary shaft and which are slidable with convex segments in concave recesses of the rotary shaft in its longitudinal direction. By a displacement of the shells in the longitudinal direction, the segments slide in the recesses, and are pushed radially to the outside. With this radial movement, the segments pick up the shells connected thereto, whereby the desired enlargement of the diameter of the rotary shaft is achieved, thus subjecting the interior surface of the support for the rolled material over its complete length to a press fit. The press fit permits utilization of very thin and therefore cheaper cardboard supports. For the automatic return of the shells into starting position when the energy for longitudinal sliding is no longer present, it is preferred to preclamp or bias the shells in radially inward direction by spring elements, e.g., spiral springs which are placed in tangential grooves around the shells.
Instead of a mechanically expandable shaft, a pneumatically expandable shaft can be used; in this case the required compressed air would be delivered via appropriate connections.
The invention will be more completely understood by reference to the following detailed description.